Keyboard crosspoint encoder having N-key rollover

Claim 2

In a crosspoint encoder of the type having an information storage device and rows and columns of conductors which define a matrix of crosspoint switches, a method of operating the encoder comprising the steps of: a. scanning the rows and columns to detect the status of each crosspoint switch and storing this information in an array in the storage device; b. determining whether a phantom switch condition exists in the array; c. reversing the status of any crosspoints which are involved in a phantom switch condition; and d. providing an output of the array.

Claim 3

In a crosspoint encoder of the type having an information storage device and rows and columns of conductors which define a matrix of crosspoint switches, a method of operating the encoder comprising the steps of: a. initiating a history array in the information storage device; b. scanning the rows and columns to detect the status of each crosspoint switch and storing this information in an array in the storage device; c. determining whether a phantom switch condition exists in the array; d. reversing the status of any crosspoints which are involved in a phantom switch condition; e. comparing each crosspoint in the array to the corresponding crosspoint in the history array; f. providing an output of each crosspoint in the array which indicates a closed switch and whose correspondent in the history array does not indicate a closed switch; and g. updating the history array by reading all the data from the array into it.

Claim 4

In a crosspoint encoder of the type having an information storage device and rows and columns of conductors which define a matrix of crosspoint switches, a method of operating the encoder comprising the steps of: a. initiating a history array in the information storage device; b. scanning the rows and columns to detect the status of each crosspoint switch and storing this information in an array in the storage device; c. determining whether a phantom switch condition exists in the array; d. reversing the status of any crosspoints which are involved in a phantom switch condition; e. comparing each crosspoint in the array to the corresponding crosspoint in the history array; f. providing an output of each crosspoint in the array which indicates a closed switch and whose correspondent in the history array does not indicate a closed switch; and g. updating the history array by reading all the data from the array into it.

Claim 5

The method of claim 1 or 2 wherein the step of determining the existence of a phantom switch condition comprises the steps of selecting a pair of rows in the array, comparing the information in each column position of the rows to determine if there are two columns where each row indicates a closed crosspoint switch, and repeating the above selecting and comparing steps until all combinations of row pairs have been selected.

Claim 8

A crosspoint encoder of the type having rows and columns of conductors which define a matrix of crosspoint switches, comprising, means for detecting which crosspoints are closed, means for determining whether a phantom switch condition exists and means for providing an output of those crosspoints which are not involved in a phantom switch condition.

Claim 9

A crosspoint encoder of the type having rows and columns of conductors which define a matrix of crosspoint switches, comprising, means for detecting which crosspoints are closed, means for determining whether a phantom switch condition exists and means for providing an output of those crosspoints which are not involved in a phantom switch condition.

Claim 10

A crosspoint encoder of the type having rows and columns of conductors which define a matrix of crosspoint switches, comprising an information storage device, means for detecting and storing in an array in said storage device the status of each crosspoint switch, means for locating a phantom switch condition in said array and for removing only switches involved in a phantom switch condition from the array, and means for providing an output of the array.

Claim 11

A crosspoint encoder of the type having rows and columns of conductors which define a matrix of crosspoint switches, comprising an information storage device, means for detecting and storing in an array in said storage device the status of each crosspoint switch, means for locating a phantom switch condition in said array and for removing only switches involved in a phantom switch condition from the array, and means for providing an output of the array.